I experienced something along these lines.. I got a bit brazen and did some large charges and they basically just flagged the entire month of charges at that retailer and put the onus of proof on me by asking me to submit receipts if I believe their assessment was in error. When they did the clawback, they had to have divided by $505.95 as their clawback figure was 100% accurate, to the penny. Without L3 data, there would have been no way to do it precisely as I often had other grocery items mixed in.

-b.